It's a sellout, of sorts, for the new Firefox OS phones. The qualification is that the phones, which went on sale Tuesday, are developer preview phones.

The two models are the lower-end Keon, priced at $119, and the higher-end Peak at $194. Both are available from the Spanish retailer Geeksphone, on whose site each phone is currently marked as "no longer in stock" after having been on sale for a few hours on Tuesday. There are reports that more developer units will soon be offered for sale online.

The Keon features a 3.5-inch, 480x320 screen, a 1 GHz Snapdragon processor, 512 MB memory, a 3-megapixel camera and 2G/3G connectivity, while the Peak has a 4.3-inch, 960x540 display, dual-core 1.2 GHz Snapdragon S4 processor, 8-megapixel camera on the back and a 2-megapixel on the front, and 512 MB of memory.

Keon Specs Similar

The devices are intended for use in testing by Firefox OS developers. Mozilla, which is behind Firefox OS, told news media that the specs of the Keon developer model are very similar to what is expected in release models, while the Peak is a bit more high-end than what will be available in the first round of releases.

Alcatel One Touch, ZTE, Huawei, Sony and LG have committed to manufacturing models using this platform, and carriers Telefonica, Etisalat, Smart, Spring, Telecom Italia, Deutsche Telekom, China Unicorn and Telenor are also on board.

While Google's Android and Apple's iOS are the first- and second-place platforms by far, there's a battle waging for third and possibly fourth place. Firefox OS offers two major strategies for overcoming Windows Phone's and BlackBerry's head start and resources.

First, Firefox OS devices are targeted at emerging markets, where the smartphone market is not as saturated as elsewhere. Mozilla and others have said their intention is to provide inexpensive, full-featured smartphones to those markets, reportedly priced about the same as feature phones.

'Sounds Wonderful'

Mozilla has said that Firefox OS includes "all the things people need from a smartphone out of the box -- calls, messaging, e-mail, camera and more," in addition to built-in social connections to Facebook and Twitter, location-based services, "a new ability to discover one-time user and downloadable apps," and, of course, the Firefox browser.

Second, instead of native apps written for a specific platform, the platform is designed for Web apps written in HTML5, which is already widely used on the Web. Reportedly, developers can adapt existing Web HTML5 apps by adding a particular kind of file about the app. Unlike other Web apps for mobile devices, HTML5 apps for Firefox OS devices will have access to core device functions, such as the camera.

Avi Greengart, an analyst with industry research firm Current Analysis, said one question is whether a $100 Firefox OS phone will be any better than a $100 low-end Android phone, the latter of which, he added, is usually "a lousy phone." In terms of HTML5 apps, Greengart said he was withholding judgment until he saw the number and quality of apps.

But, "hypothetically," he said that if a $100-ish Firefox OS smartphone was good quality, if there were a sufficient number of good quality HTML5 apps, and if it can avoid direct competition with the biggest players by focusing on emerging markets, then "it sounds wonderful."